Construction and earth-moving machines are often propelled by continuous tracks. Such machines may be used to move materials such as soil, rock, gravel, sand, asphalt, and the like during the construction or maintenance of paved surfaces, building sites, landscapes, mines, or other areas. For example, track type tractors and excavators propelled by continuous track may be used to excavate earth, transport earth and/or building materials, smooth and grade surfaces, and demolish old structures. Typically, such machines include a chassis which supports an engine and an operator cab. An undercarriage supports the chassis and includes a pair of continuous tracks propelled by drive wheels and supported by undercarriage track rollers. The undercarriage track rollers may include a shaft, a rim that turns relative to the shaft and directs continuous track, and a collar that retains the roller on the shaft via internal seals.
During a work cycle, an undercarriage track roller may become fouled with soil, rocks, pebbles, and other debris from the worksite. For instance, an undercarriage track roller may be configured so that debris may become packed between the rim and the collar. Such debris may eventually damage the internal seals, thereby jamming the undercarriage track roller. This situation requires stopping work, removing the undercarriage track roller from the machine, and disassembling the undercarriage track roller to clean out the packed debris and repair the internal seals. Otherwise, the undercarriage track roller may be monitored and preventively removed from the machine and disassembled to unpack the accumulated debris before the internal seals are damaged. A jammed undercarriage roller may also result in damage to the continuous track and propulsion system of the machine.
Undercarriage track rollers that attempt to prevent fouling are available. Such undercarriage track rollers are often arranged with a tight spacing between the collar and the rim meant to keep debris away from the internal seals. More specifically, the collar and the rim are equipped with corresponding labyrinthine structures to impede the ingress of debris while allowing the rim to rotate relative to the collar. However, these efforts to prevent undercarriage track roller fouling have been largely ineffective. It has been found that fine particles of debris have a tendency to enter the space between the rim and the collar despite the tight labyrinthine spacing. Then, because of the tight labyrinthine spacing, these fine particles cannot escape. The fine particles therefore accumulate between the collar and the rim, leading to the aforementioned packing and eventual damage. One example of an existing strategy for attempting to prevent undercarriage track roller fouling is shown by Jackson in U.S. Pat. No. 8,356,680.
It can therefore be seen that improvements in the arrangement of the rim, collar, and associated structures are desired to reduce complexity while still preventing fouling of the undercarriage track roller. Furthermore, reduced complexity may improve reliability, increase assembly efficiency, and reduce cost.